# PWR moderator

Changes PWR neutron moderation.

Place the object under `traits` in a fluid-property file.

## Fields

| Field | Meaning and default | Range |
| - | - | - |
| `multiplier` | PWR neutron-flux multiplier. | finite `f64` |

## Example

From `data/hbm/fluid_property/heavywater.json`:

```json
{
  "pwrmoderator": {
    "multiplier": 1.25
  }
}
```